Ledge block



Jan. 1, 1935. I R, SHELLENBERGER 1,986,670

' LEDGE BLOCK Original Filed Dec. 10, 1951 2 Sheets-Sheet l v INVVENTOR 1209?? Shellenberger BY ms ZTORNEY *Jan. "1, 1935 R. SHELLENBERGER LEDGE BLOCK .Og'iginal Filed Dec. 10, 1931 2 Sheets-Sheet 2 INVENTOR g gslwaemrger HjS ATTORNEY Patented den. 1, 1935 LEDGE BLOCK Rolfe Shellenberger, Westfield, N. .Llassignor to Fuller Lehigh Company, New York, N. Y., a corporation of Delaware I Application December 10, 1931, Serial No. 580,129

A Renewed November .22, 1934 11 Claims.

My invention relates to furnace walls, andmore particularly to means associated with the interior face of such walls for the purpose of influencing materials within the furnace. As a matter of convenience, the means referred to will be designated as ledge blocks.

The present application is a continuation in part of a pending application Serial No. 496,858, filed November 20, 1930, by Ervin G. Bailey, Rolfe Shellenberger and Dana H. N. Mayo, for Furnace,

One object of the invention is the provision of means adapted to change the direction of move ment of material within the furnace. A further object is the provision of a member, in association with the furnace wall which may act to protect the wall from the action of certain materials within the furnace. Other objects will be apparent from the description given in this specification.

20 The invention is illustrated by way of example in the accompanying drawings wherein- Figure 1 is a vertical section through part of a boiler and furnace constructed in accordance with the invention, i

Fig. 2 is a vertical section through part of a furnace wall and bottom showing a different form of the invention,

Fig. 3 is a section similar to Fig. 2 illustrating another embodiment of the invention,

Fig. 4 is a vertical section of part of a furnace wall andbottom in which yet another variation of the invention is illustrated,

Fig. 5 is a perspective view of the embodiment illustrated in Fig. 3, and

Fig. 6 is a section on the line VI-VI of Fig. 3 illustrating a method of attaching ledge blocks to wall tubes.

According to the invention, the ledge blocks may be positioned entirely above the furnace floor, at the level of the furnace floor, or partly below the furnace floor. In any case liquid ash or slag which rolls down the inside of the furnace wall will continue along the upper face of the ledge block, being directed inwardly of the furnace thereby.

Where the ledge block is positioned entirely above the furnace floor, the slag flowing over its upper surface will drop to the furnace floor and may thus be caused to clear any construction lying immediately below the ledge block.

Where the ledge block is on the level of the furnace floor, that is to say, where the lower edge of the ledge block is at the furnace floor level, its lower face may contact with the upper surface of the floor. It will be obvious that if the I109! it expands.

moves with relation to the ledge block a shearing action between the floor and the ledge block will result. Thus, if a layer of solidified or semisolidified slag overlies the furnace floor, and if the floor or the slag, or both, tend to expand out- 5 wardly, the ledge block will act to shear the slag from the surface of the furnace floor. To make this action more effective I may provide an outer portion of the furnace floor composed of dense blocks, for instance, refractory blocks, which are in contact with the lower surface of the ledge blocks.

It has been found that when a furnace which deposits slag in its bottom is shut down, the slag cools, solidifies and checks, large open cracks being formed in the slag layer. If the furnace is again put into operation, the checks or cracks may be filled before the solidified slag is melted. As the solid slag in the furnace bottom is heated Being unable to expand into the cracks therein because they are filled, the solid slag expands or grows outwardly. Such expansion has been responsible for displacing the walls of a furnace in whose bottom slag is deposited, and the seal between the furnace floor and the walls has thus been broken and furnace operation handicapped thereby. Where ledge blocks are employed, the expanding slag layer is sheared from the furnace floor and deflected upwardly along the upper surface of the ledge block. The layer of expanding slag thus has only ,a slight horizontal component as a result of its expansion, the force producing the expansion being largely spent in pushing the slag edges up-. wardly along the ledge blocks.

Where a granular refractory forms the furnace bottom, slag may penetrate into this material and upon cooling and again expanding,.force the material itself outwardly. In such constructions the ledge block may be positioned w th its lower surface and inner edge beneath the surface of the refractory so that when the latter expands or grows, it will move upwardly in the furnace along the inclined surface of the ledge block and 45 will not exert undue force normal to the furnace wall.

The ledge blocks are preferably mounted in good thermal contact with tubes carrying a cooling fluid in the walls. Whilethe ledge blocks may be constructed of any convenient material consistent with the conditions to be withstood, it may be here remarked that it has been found of advantage to form the ledge blocks of metal or carborundum or other material having high heat lugs and especially to Figure 1, it will be seen that there is there shown a' furnace 10 having water walls 11 comprisingwater tubes 12 and a covering of refractory blocks 13 thereon, A furnace floor 14 isprovided, comprising a series of layers 15, 15 of granular refractory material overlying which a layer of slag 16 is shown, but it is to be understood that the furnace floor, in any case, in-

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' and the wall.

eludes slag resistant material, whether it be metal or other refractory material. In other words, the floor must contain materials which are sufliciently resistant to destruction by slag that a pool of slag may be maintained in the bottom of the furnace.

Ledge blocks 1'7 are shown associated with the wall 11 projecting inwardly from the inner surface cf the wall. These ledge blocks are substantially horizontal members preferably of triangular a horizontal direction; In the form illustrated in Figure 1, the lower surface and inner edge of the ledge block is beneath the surface of a granular refractory layer 15. In consequence, if slag penetrates this layer of refractory material and pushes it outward, the ledge block will cause the edges of the layer to move upwardand will not permit excessive pressure upon the furnace wall.

Obviously, such ledge blocks might be mounted on fluid cooled conduits other than wall tubes.

In the form illustrated in Fig. 2, a dense block 18 is .disposed at the edge of the furnace floor, and the lower surface of the ledge block 1'1 is in contact with the upper surface of this dense block. Slag 16 is deposited above the furnace floor and the dense block 18, extending upwardly along the lower surface of the ledge block 17. When the slag 16 freezes, and expands upon being reheated, it grows along the upper surface of the ledge block 17. Ashearing action is provided between the lower surface of the ledge block 17, and the upper surface of the dense block 18, and thus slag is prevented from passing between the floor and the ledge block. 1

In the form illustrated in Fig. 3, the ledge block 1'7 is positioned entirely above the furnace floor and above the normal slag level. In this construction the ledge block acts merely to direct slag which flows down the furnace walls 11 inwardly of the furnace, and to prevent the slag from working its way between the furnace floor and wall while in highly molten condition. In this position the ledge block also protects the edges of the slag pool 16 from the direct influence of'the flame, so that slag beneath the lower surface of the ledge block will be less fluid than slag in the middle of the furnace floor, and will, therefore, have a slighter tendency to penetrate between the floor Furthermoreythe ledge block itself tends to cool the material with which it is in contact. The floor materials around the edges of the furnace are, therefore, kept cooler than they would he were the ledge blocks not present.

It may be desired to pass air through the ledge blocks. An example of ledge blocks through which air may be passed is illustrated in Fig. 4. Here the furnace floor 14b is. cooled by having air passed through the refractory itself. overlying thegraimlar refractory 15c is a layer of material 19 which is impervious to-air. By projecting air into the fumace floor below this upper layer 19 and by providing ports 20 extending through the ledge blocks 17a to a point below this impervious layer 19 but in the porous granular material 15c, air passes through the furnace floor, cooling it, and thence passes outwardly to the walls and upwardly through the ports in the ledge blocks. Some cooling of the ledge blocks themselves may be effected in this way In the examples illustrated in the drawings the furnaceewalls comprise water tubes and blocks fastened to the water tubes, as previously explained. The-ledge blocks are shown as also being fastened to the water tubes, and of course, may form one row of blocks covering the tubes. The invention is not limited, however, to this construction. v

Other forms of the invention, differing in detall but not in principle from those shown in the drawings and specifically described above, will readily suggest themselves to those skilled in the furnace art. The examples here given and described are presented merelyto illustrate how the invention may be applied, and are not to be construed as limiting the scope of the invention. With this understanding, therefore,

I claim:

1. In a furnace, a wall including water tubes and slag resistant material associated with said water tubes to form the wall, a slag resistant furnace floor extending in proximity to said wall, and a'row of wedge-shaped blocks of heat conducting material fastened to said water tubes and extending from said wall inwardly of the furnacein contact with said floor, said blocks being movable relative to the floor.

2. In a furnace, a wall including cooling tubes, a substantially horizontal floor portion, the latter adapted to sustainan expansible layer deposited as 'a result of furnace operation, and marginal slag deflectors secured to tubes of the furnace wall and extending over the floor and shaped to deflect the marginal portion of the aforesaid deposited layer from the normal unexpanded position and with a minimum pressure transmitted to thewall upon heating, the slag deflectors being located adjacent the floor of the furnace.

3. In a furnace of the class described, opposed walls at least one of which includes wall cooling tubes, means for burning a slag forming fuel in the furnace, a substantially horizontal furnace floor extending between saidwalls and adapted to support an expansible layer of slag-like material resulting from combustion in the furnace, slag resistant material associated with the tubes above the floor, fluid cooled ledge blocks having wedge shaped portions extending inwardly of the inner surfaces of the walls and having their apices presented above the floor so as to contact with said layer and cause it to be forced upwardly as it expands, and means for securing the ledge blocks on the tubes below said slag resistant material and in heat conducting relationship therewith.

4. In a furnace, a floor, a wall comprising water tubes, slag resistant material associated with said water tubes to form the wall, and a row of wedge-shaped ledge blocks fastened to said water tubes adjacent said floor having their apices extending from said wall inwardly of the furnace floor. l

5. In a slag tap furnace, opposite walls at least one of which includes water tubes, a furnace floor extending from wall to wall and adapted to maintain a thin slag layer extending across the furnace, and slag resistant and'heat transmitting blocks attached to said water tubes and having extensions projecting inwardly of the furnace in the slag zone thereof, said block extensions having downwardly sloping upper faces and being cooled by said water tubes.

6. In a furnace, a wall, a furnace floor, and a fluid cooled member of substantially wedgeshaped cross-section associated with said wall and projecting inwardly from the inner surface thereof, the bottom face of said member adjacent the floor and providing a shear surface in contact with slag on the floor, and the top face of said member being inclined upwardly toward said wall.

'7. A furnace wall comprising spaced water tubes, means to close the spaces between said tubes, a floor extending from the wall, a row of ledge blocks fastened to said water tubes and having wedge-shaped portions with their apices presented inwardly of the furnace wall near the floor of the furnace, and means for burning a slag forming fuel in the furnace, the furnace floor being adapted to maintain a layer of slag in the furnace.

8. In a furnace of the class described, walls including wall cooling tubes, means for burning a slag forming fuel in the furnace, a horizontally extending furnace floor between said walls adapt-- ed to support an expansible layer of slag-like material resulting from combustion in the furnace, slag resistant material associated with the tubes above the floor, fluid cooled ledge blocks having wedge-shaped portions extending inwardly of the inner surface of said material and having their apices presented above the floor so as to contact with said layer and cause I it to be forced upwardly as it expands, and means for securing the ledge blocks on the tubes and in heat conducting relationship therewith, the ledge blocks being formed with passages communicating with a pervious floor layer through which air or a gas may be forced.

9; In a furnace of the class described, opposed walls at least one of which has wall cooling tubes,

. ineans for burning a slag forming fuel in the furnace, a furnace floor extending transversely of said walls to.=support as a pool an expansible layer of slag-like material resulting from combustion i'nthe furnace, slag resistant material associated with the tubes above the floor, fluid cooled ledge blocks *having obliquely surfaced portions extending inwardly of the inner surface of a wall and having their oblique surfacesp'resented above the floor so as to contact-with said layer and cause it to be forced upwardly as it expands, and means for securing the ledge blocks on the tubes below said material and in heat conducting relationship "therewith.

10. In a furnace, a'wall comprising water tubes and slag resistant materials associated with the tubes, aslag resistant furnace floor extending in proximity to the wall, and a row of wedge-shaped blocks fastenedto said water tubes and extendingalong the floor from the wallinwardly of the furnace and beyond the inner surfaces of the material.

11. In fluid heat exchange apparatus, a furnace the walls of which include fluid fllled tubes, means for burning fuel in the furnace under slag producing conditions, a slag resistant furnace floor, and slag resistant material bonded to the tubes on their hotter sides and forming an inclined ledge at the floor extending over the junction of the floor and a wall, said ledge being inclined so as to produce an upward thrust on a slag layer formed on the floor.

ROLF'E SHELLENBERGER. 

